We demonstrate “pick and place” integration of a Si3N4 microdisk optical resonator with a single-photon-emitter (SPE) host in the form of ~20-nm-thick hexagonal boron nitride (hBN). The film folds around the microdisk maximizing contact to ultimately form a composite hBN/Si3N4 structure. The local strain that develops in the hBN film at the resonator circumference deterministically activates a low density of SPEs within the whispering gallery mode volume of the microdisk. These conditions allow us to demonstrate cavity-mediated excitation and incipient coupling of hBN color centers to the microdisk cavity modes.

We examine the dynamics of NV-P1 spin pairs under under continuous optical excitation , and theoretically show that cross-relaxation between the NV and P1 spins must induce rigid rotation of the diamond crystal. Further, we find that physical rotation introduces a distance-independent coupling between remote spin pairs, which can ultimately lead to entanglement between otherwise non-interacting NV-P1 pairs.

We demonstrate efficient microwave-free 13C DNP via consecutive magnetic field sweeps and continuous optical excitation. By comparing the 13C DNP response for different crystal orientations, we show that the process is robust to magnetic field/NV misalignment, a feature that makes the present technique suitable to diamond powders and settings where the field is heterogeneous. Applications to shallow NVs could capitalize on the greater physical proximity between surface paramagnetic defects and outer nuclei to efficiently polarize target samples in contact with the diamond crystal.

We study the case of an NV center in diamond interacting with a near-surface paramagnetic defect (P1), in turn coupled to protons outside the diamond crystal. We theoretically show that protons spin-polarize efficiently upon a magnetic field sweep across the NV–P1 level anti-crossing. The polarization transfer process is robust to NV misalignment relative to the external magnetic field, and efficient over a broad range of electron-electron and electron-nuclear spin couplings, even if proxy spins feature short coherence or spin-lattice relaxation times.

We articulate experiment, theory, and numerical modeling to shed light on the optical pumping of 13C spins in an NV-hosting diamond powder subjected to simultaneous laser excitation and MW frequency sweeps. The understanding we gain should help expedite applications where powders are intrinsically advantageous, including the hyper-polarization of target fluids in contact with the diamond surface or the use of hyperpolarized particles as contrast agents for in-vivo imaging.

Here we demonstrate variable-magnetic-field cross-polarization from the NV electronic spin to protons in a model viscous fluid in contact with the diamond surface. Our experiments suggest slower molecular diffusion at nm distances from the diamond surface compared to that in bulk, an observation consistent with present models of the microscopic structure of a fluid close to a solid interface.

Using multi-color confocal microscopy, we show that near-surface NVs ionize and recombine via single-photon processes due to concentration-dependent state hybridization with orbitals from neighboring traps. Further, we observe charge transfer from and to NVs in the dark which we reproduce semi-quantitatively via Monte Carlo modeling. These findings can find application for nanoscale electro-chemical sensing, or for data storage with sub-diffraction resolution.

Dynamic polarization of nuclear spins via optically pumped NVs is an intriguing route to enhanced-sensitivity NMR but applications have been limited to single crystals. Here we attain record levels of 13C spin polarization in powdered diamond under ambient conditions. These results pave the way towards the use of hyperpolarized diamond particles as imaging contrast agents for biosensing and, ultimately, for the hyperpolarization of nuclear spins in arbitrary liquids brought in contact with their surface.

One of the most remarkable properties of the nitrogen-vacancy (NV) center in diamond is that optical illumination initializes its electronic spin almost completely, a feature that can be exploited to polarize other spin species in their proximity to record levels under ambient conditions. Here we show 13C spin pumping near 51 mT takes place via a multi-spin cross relaxation process involving the NV– spin and the electronic and nuclear spins of neighboring P1 centers.

The silicon-vacancy (SiV) center in diamond is emerging as a new platform for nano-photonics, information processing, and sensing but the controlled conversion between its most common charge states (negative and neutral) has so far proven elusive. Here we demonstrate on demand generation of SiV- and SiV0 over large areas using laser excitation of variable wavelength and intensity.

We demonstrate strain-induced activation of single-photon emitters in hexagonal boron nitride into a bright state through charge trapping in deformation potentials. The process is nearly 100% efficient yielding stable emitters at room temperature over arbitrarily shaped spatial patterns. This article was chosen for Optica’s cover.

Coherent communication over mesoscale distances is a necessary condition for the application of solid-state spin qubits to scalable quantum information processing. As an initial step in this direction, here we make use of room-temperature spin waves to mediate the interaction between the microwave field from an antenna and the spin of an NV center 3.6 mm away.

In nanoscale metrology applications, measurements are commonly limited by the performance of the sensor. Here we use a hybrid quantum-classical sensor device to demonstrate NMR spectral resolution of single spins down to 13 Hz. This work paves the way for high resolution NMR spectroscopy on nanoscopic quantum systems down to the single level.

We use NV centers in diamond to demonstrate high-density, three-dimensional read/writing of classical information. We also show how nuclear spins can serve as ancillary memories for sub-diffraction data encoding.

We investigate the diffusion and trapping of charge carriers photo-ionized from NVs and P1 centers in diamond. We observe the formation of intriguing patters that we reproduce semi-quantitatively via a model of coupled master equations.

We work with NV centers nanometers below the crystal surface to probe the near-surface dynamics of molecules from organic systems including solid films and liquids. For the latter group, we manage to separately identify adsorbed and freely diffusing molecules.

We demonstrate efficient spin polarization transfer from NVs to P1 centers in their vicinity. Further, using the NVs as a local probe, we determine that the P1 center spin polarization reaches up to 50% within a 10 nm volume centered at the NV.

We introduce a new NV-based technique to probe weakly coupled nuclear spins. Unlike prior approaches, this method exploits the long NV spin-lattice relaxation times to attain highly-resolved NMR spectra from the nuclear spin noise.

We use the large magnetic field gradient to image the nuclear spin polarization induced by optical pumping of a gallium arsenide wafer. We show that low illumination intensities generate a non-monotonic polarization profile where nuclear spins polarize positively or negatively, depending on the distance to the sample surface.